[Publications]

‘Biological ©
& Medical

TILTH # TILLAGE

iP

KHAKI UNIVERSITY OF CANADA
Series 1.—No. 4.

‘

KHAKI UNIVERSITY OF CANADA

1918

TILTH & TILLAGE
ee -IHE SOIL

Fic. 35.—Good tilih of soil. (Double sulky plough, an
- «wmplement that is increasing in favour for level land).

Reprinted, with adaptations, from “TILTH AND TILLAGE
OF THE SOIL,” by Elmer O. Fippin, in ‘Cornell Reading

Courses.”

oners, —

42-60, Goswell Road,

rs-and Stat
London, E,C. 1.

J.C. KING, LtD.,

Prin

TILTH AND TILLAGE OF THE SOIL

ELMER O. FIPpiIN

A g6éod soil should provide a congenial place for the
development of plant roots. It should be deep enough
to permit their normal spread. It should carry the right
amount of water, maintain a satisfactory temperature,

Fig 36.—Section of soil showing natural structure and the
- distribution of grassroots. It shows, also, idecl ploughing:
the action of the mouldboard in twisting the furrow slice ;
and the action of the jointer in turning under the edge ©,
the furrow. Rather large spaces occur between the furrow
slices adjacent to the subsoil. At the lower right-hand side
is an enlarged view of a section of the subsoil showing
distribution of cracks, root cavities, and burrows of worms.

3

and have adequate ventilation. It should have a chemi-
cal nature that will be congenial to plant roots and to
useful organisms in the soil, and should supply the food
required for plant development. These conditions
should be maintained as evenly as possible. Not only
are changes injurious in themselves, but one unfavourable
condition will induce another.

That layer of soil in which the roots of plants are
distributed and in which all the physical, chemical,
and biological processes are most active is termed the
root-zone. (Fig. 36.) For crops most commonly grown
the root-zone should have a depth of at least three feet.

TILTH

The factor that most often determines the adjustment
of all these conditions of the soil is physical structure.
Soil is a frame-work of particles of rock and organic
matter through which many small spaces or pores are
distributed. By their size, volume, and distribution,
the spaces regulate the other. properties of the soil.
If the particles are small, the open spaces are correspon-
dingly small. Spaces that are too small are likely
to be continually full of water, which crowds out air
and creates bad ventilation. Poor ventilation, in turn,
smothers or prevents the development of roots and
bacteria. This interferes with the food supply and is
injurious in many other ways. lf the spaces at the sur-
face of the soil are too small the water that comes as rain
does not find ready admission andis lost, so that the crop
may later suffer from lack of water which should have been
absorbed. Further, soil spaces that are too small,
if clogged with water and consequently poorly ventilated,
promote chemical and biological processes which are
decidedly harmful. Thus, nitrogen in the form of nitrate

-

ee

ALFALFA CORN

FEET OEPTH

Fic. 37.—Types of root systems showing different forms
and depths of penetration. Deep-rooted plants are
an effective means of improving the structure ©, f hard
but well-drained subsoils.

fertilizer may be broken down to the condition of a
free gas, so that it cannot be used by many kinds of
plants. Excessive absorption of water due to very
small spaces renders the soil cold, and from this arises
a chain of injurious results. This brief explanation
shows how important is that physical condition of the
soil which gives the right size and proportion of pore
spaces.

The physical nature of the soil is referred to as tilth.
The most advantageous character and arrangement
of the soilis termed good tilth, while the reverse condition
is termed bad tilth, The maintenance of good tilth
should be the first object of the farmer. Consequently
he should understand that physical basis on which good
tilth rests and the practical means by which it is regulated.
This lesson is devoted to a brief explanation of the physi-
cal basis, of the things that most directly affect it, and
of the action of the more common implements of tillage
in their relation to these properties.

As has been indicated, good tilth is identified with
the right size of pore space throughout the soil mass.
These pores depend for their size on the size and arrange-
ment of the particles of soil. The particles of soil are
of many sizes. The term used to refer to the size
or fineness of the individual particles of soil is teature.
A fine-textured soil is one made up mostly of very small
particles. A gravelly or a sandy texture is one made

up of large particles.

The arrangement of the separate pariecled in a soil
is termed structure. Soils may have a loose or a compact
structure. Clay in a fine, friable condition easy to stir
may be said to have a loose structure. If the separate
particles are gatheredin groups or kernels such a structure
is termed granular. But the same soil when mixed

6

and stirred in a wet condition becomes very dense, and
such asoilis said to have a compact, or puddled, structure.

Texture of soil

Not only are soils made up of particles of different size,
but each soil contains particles of many different sizes.
These different sizes have been classified into groups
and each division has been givenaname. The divisions
most frequently used are as follows :

TABLE 1

TEXTURAL DIVISIONS OF SorL MATERIAL

Size in

Name Spare oh oe Size in inches
J ae eee | Above 50 Above 2
Coarse gravel .. | 50 to 10 2 to 1/4
Medium grave!.. 10 to 2 1/4 to 1/12
Fine gravel... | re) a 1 /12 to 1/25
Coarse sand .. Ere) os 1/25 to 1/50
Medium sand .. 2) nb 1/50 to 1/100
Fine sand.. .. .25to .10 | 1/100 to 1/250
Very fine sand.. -l10to .05 | 1 /250 to 1/500
Pipes os. -- | -O5to .005| 1/500 to 1 /5,000

oo Bi Sr . Below .005 Below 1 /5,000

It will be noted that there are more divisions of the
small particles than of the large ones. The finer the
particles are, the greater is their effect on the properties

S/L7 LOA/A CLAY LOAM
*4INE GRAVEL AWD COARSE SAND SOS

AIEDIUM AND FINE SAND
VERY FINE SAND

SA7

CLAY

Fic. 38.—Diagrams representing the textural compost-
tion of the more important classes of soil, and the
proportion of particles of different sizes that make up
each kind.

of the soil in proportion to their volume. Sand is
gritty and does not stick together, especially when dry.
Silt is flourlike, but not gritty; and the particles have
little tendency to stick together. Clay is powdery,
and when wet usually becomes very sticky. When
dry it hardens and bakes. The clodding of soil is
evidence of the presence of clay, although it does not
necessarily mean pure clay. A loam soil worked when
wet may clod badly.

On these textural groups are based many of the
descriptive terms in common use. (Fig. 38.) A sand
is soil one made up essentially of sand particles with
so small an amount of silt and clay that the latter are
negligible. A claysoilis onein which clay particles prevail
to such an extent that the soil acts like pure clay. A
silt soil contains so much material of the size of silt
that it acts essentially like pure silt. A loam soil
is one made up of such proportions of all grades of
material that no one of them is dominant. If soil is
loamy but has one constituent predominant, it may be
termed accordingly a sandy loam, a silt loam, a clay
loam, or perhaps a silty clay loam. Thus, there may
be a great variety of combinations of these materials,
giving rise to many classes of soil based on their fineness.

Because of the influence of texture on the properties
of a soil and consequently on its relation to plants,
soils have sometimes been named according to the kind
of crops to which they are suited. For example, wheat
soils are generally of a clay-loam texture. The best
grass soil is usually a heavy clay. Corn does best on
a loam or a sandy loam, and early truck crops are grown
on light sandy loam soil.

In a soil of coarse texture the pa-ticles of soil are free,
one from the other, and rest together as a loose mass.

7

This is well seen in clean sand and in gravel. The size
of the pores in the soil is dependent on the size of the
particles, and the larger the particles are, the larger the
pores will be. For example, the spaces between buck-
shots are larger than the spaces between bird shots.
The total volume of the spaces in a quart of material
in either case is approximately the same. If, however,
the two kinds of shot are mixed together, they will
occupy less space than two quarts taken separately,
because the small shot partially fill the spaces between
the large shot. If, on the other hand, a few of the large
and a few of the small shot were fastened together in
bunches and these bunches were brought together, they
would be found to occupy more space than either of the
_ other arrangements.

Structure of soil

The above illustrates how the arrangement or structure
of a soil affects pore space and consequently crop-pro-
ducing properties. Soils are made up of particles of
different sizes, and there are the possibilities of arranging
them with granular open structure, or with puddled
compact structure. The finer the soil particles are, the
greater possibility there is of changing the nature of the
soil by changing the arrangement of the particles. Loam ~
and clay soils are the most difficult to manage because
they easily form large, hard lumps or a compact,
impervious mass.

A layer of soil that is particularly dense and difficult
to penetrate is termed “hardpan.” Many things may
give rise to this condition. Streaks of clay sometimes
produce such a result. In the hill soils of Southern New
York, large areas of land have a compact subsoil or
hardpan composed of shale chips and silt or clay loam

10

closely mixed together. Where the climate is arid, in
the western States, the soluble salts sometimes accu-
mulate in layers and cement the soil particles, forming a
condition of hardpan.

In soils of a clayey nature the arrangement that is
most desirable is a fine, granular structure. This has
been termed crumb structure. (Fig. 35.) If the particles
are separate and rest together naturally, they torm a
mass that is too dense for good results. On the other
hand, if they are gathered into large chunks, the con-
dition is objectionable because the spaces are too large.
Such lumps are called clods. Between these extremes
is the happy medium which produces a size and volume
of pores that is the most serviceable. It is likely to vary
somewhat according to the soil-water conditions, the
season and the kind of crop grown ; but these differences
can generally be disregarded.

The object in handling all kinds of heavy soil should
be to develop a fine, friable, granular tilth which is easy
to manipulate and efficient in absorbing and holding
water and in permitting the penetration of roots.

Pore space

Much has been said about pore space in the soil. A
soil is made up of several materials. Chief of these are
the soil particles, water, and air. A fertile soil for the
staple upland crops must have a proper proportion of
each of these constituents. If there is too much soil
there may be a deficiency of water or air, or both,
according to the division of this space. If there is too
little soil, the proportion of pore space is excessive. If
the spaces are large, as they are likely to be, they permit
leaching and retain insufficient water for the needs of
plants; and the excessive ventilation and the high

1]

temperature that result cause a wasteful decay of organic
matter. While heavy clay, on the other hand, may have
a larger total volume of pore space, it has the space
much more subdivided, so that itis effective in absorbing
and holding water. When puddled, the pores become so
small and the water is held so tenaciously that it is of
little service to plants. ?

Fic. 39.—An iliustration of soil in bad tilth, and of poor
ploughing. The soil is heavy clay and was much too wet
io be ploughed effectively. The shining surface at the
bottom of the furrow slice indicates the presence of too
much water. Several seasons of careful tillage will be
required to overcome the bad effect of such practice.

The importance of the right proportions of these three
constituents and of their relation to texture and structure
of soil is well sown in the diagrams in Fig. 40. In the

12

following table is given the proportion of pore space in
some common classes of soil :—

TABLE 2

PoRE SPACE IN SOIL

| Proportion of pore space
Kind of soil

_ Percentage pitas
Clean beach sand 4 | 35 to 40 1/3 to 2/5
Sandy loam. Good tilth | 40 to 50 2/5 to 1/2
Sandy loam. Puddled . 20 to 40 1/5 to 2/5
Silt. Good tilth -. | 45 to 55 3/7 to 5/9
Clay. Good granular tilth 50 to 65 1/2 to 2/3
Clay. Puddled.. 3 25 to 45 1/4 to 2/5

The average size of the pores is much more important
than their total volume, although the latter is important.
In general, it may be remembered that one-half of the
volume of soil is pore space.

The soils of the extremes of texture, as clay, sand and
gravel, and consequently of the extremes in sizes of pores,
are adapted to special crops. The soils of intermediate
fineness, and therefore of intermediate size of pores, are
suited to a wide variety of crops and types of farming.
They are used for mixed farming, and usually command
the highest prices as farm lands. These types include

13

silt, loam and the different grades of medium and heavy
sandy loam. A certain amount of granular structure
should be maintained in these latter soils, for they may

wi gee- --- ce awe

———
GRANULATED

C28}

IFELET
PERCENTAGE BY VOLUME

Fic. 40.—Diagrams representing the proportion of space
occupied by soil material, water, and air in a section of
_ different soils. The availability of the soil water and the

presence of sufficient air are dependent on the right phy-
sical condition of the soil.

develop a bad physical condition. Good tilth, which
generally implies a proper state of granulation, is there-
fore important, and attention may well be given to the
means for its maintainance.

Methods of improving tilth

Proper tilth of the topsoil may be largely effected by
tillage operations conducted at the right time and in the
proper manner. With tillage must be associated the
right moisture condition of the soil. The use of crops
and crop rotation, of manures, fertilizers and lime, is
helpful to this end.

The full depth of the root-zone cannot usually be
reached by surface tillage. Attention should be given

14

to the subsoil quite as much as to the topsoil. A subsoil
that is too dense may be improved by various indirect
means, particularly by drainage, which promotes bene-
ficial action of plant roots, of earthworms, and of other
forms of animal and insect life that live in the soil. .

Conditions which promote granulation.—The best con-
ception of the means of keeping the soil in good tilth

Fic. 41.—Soil in good tilth. The Meeker harrow ts a very
efficient pulverizing tool. It consists of a series of small
dises fitted rigidly to a straight azle.

may be obtained by a review of the factors influencing
granulation :—
1. Adequate drainage is the most fundamental of

15

these. It is impossible to keep a poorly drained soil
in good tilth. Such a soil is naturally inclined to puddle
and compact, and when dry works up into a rough,
lumpy condition. Continual wetness breaks down the
granular aggregates by dissolving the cementing material
and permits the particles to settle together. The first
step toward improvement of soil that is too compact
is provision for good drainage by some means, preferably
by tile underdrains.

Drainage quickly removes excess water and permits
a reasonable amount of drying, which results in cutting
and granulating the soil by means of checks and cracks.
Without any other treatment, drainage will loosen the
soil and provide an improved circulation of water and
gases throughout the earth mass. In proof ot this is the
observation of farmers that underdrains in heavy soil
gradually increase in efficiency over a period of years.
This mode of action has been described as a “ slacking ”’
of the soil, although technically it is a different process.
The earth seems to fall apart and loosen to such an
extent that certain persons have thought they noticed
an elevation of the surface adjacent to the lines of drain.
Too much emphasis cannot be placed on the fundamental
value of drainage in improving the physical condition of
compact soils.

2. Tillage of soil that contains only capillary (film)
water is very helpful. If the soil is either too wet or too
dry the best results cannot be obtained. (Fig. 39).

That nicely moist condition in which a mass of moist
soil pressed in the hand will hold its form but will not show
free water, is the right stage for proper tillage. When
too dry, a soil breaks into chunks, or clods, that must
be broken down.

3. Plenty of decaying organic matter in the form of

16

humus is very helpful in developing good tilth. Humus
is a dark-coloured, gelatinous substance that in many
ways helps to produce granular structure. The tendency
of soils to settle and bake after years of cultivation is
often due to exhaustion of the organic matter. This in
turn reacts on the physical and drainage condition of the
soil in a way which is doubly injurious. The main-
tenance of humus in the soil is one of the most effective
means of improving the tilth. This applies to sandy land
quite as much as to clay land, but in sand the mode of
action is different from the process of granulation.

4. Lime has a peculiar effect on clay soils. The fine
particles are thrown together in groups or floccules and
when the soil dries these become granules. Clay soils
rich in lime carbonate have sometimes been mistaken
for sandy soils because of this action. Clay soils that have
been granulated work more easily than those that have
not. An English farmer is reported to have said that
liming clay land enabled him to plough with two horses
where three had been required before. This is perhaps
an extreme result, but such a general effect of lime is well
recognized. Some commercial fertilizers affect soil in
the same way.

5. Freezing breaks up heavy soil. As water in the
soil treezes it is formed into long, needle-like crystals
that cut through the soil in many directions. If a
soil is carefully dried from its trozen condition a check
will be seen to form wherever a crystal occurred. The
network of crystals is so complete and their cleaving
action is so tremendous that the hardest clod falls to
many pieces after two or three such freezes. (Fig. 42.)
The lack of frost action is considered to be responsible
for the denser nature of soils in warm countries.

Nothing is more effective in breaking up subsoils than

17

deep fall ploughing, by means of which they are exposed
to frost action during the winter. In order to obtain
its full effect, such fall ploughing must be coupled with
good drainage. This will prevent the soil from running
together during the spring thaws.

6. Penetration of the roots of plants, and the burrow-
ing of earthworms, ants, and other forms of animal life,
are important agencies for soil improvement. (Fig. 36.)
Tons of material per acre are handled by earthworms
and ants in the course of a year. The roots of plants
press through the soil, pry their way into small crevices,

Fic. 42.—These figures represent two pans of clay soil which
had been puddled and moulded with a smooth surface.
While still wet, Pan No. 2 was permitted to freeze. Both
pans were permitied to dry out. The cracks formed where
the structure of the soil was most open. The pattern in
No. 2 shows the influence of the ice crystals, and this soil
was much more friable and crumbly than the soil that was
dried without freezing.

and cut the soil in every direction. Crops having fine,
fibrous roots, such as buckwheat, are especially noted
for their beneficial effect on heavy soil. It is generally

18

recognized that after a clay soil has developed a poor
condition by a period of unwise cultivation, good tilth
ean best be obtained by laying down to grass for a period
of years, after which the earth turns up friable and mealy.
(Fig. 37.)

The roots of plants, the earthworm, and other soil
life, operate only in moist and well-ventilated soi], as has
already been noted. If we would have their co-operation,
the land must be well drained. The mat of vegetation
on the surface formed by plants, especially grasses,
protects the soil from the beating and puddling action
of rain, from melting snow, and from washing. Plants
used tor this purpose are known as cover-crops.

TILLAGE

Principles of tillage

Tillage is the manipulation of the soil by means of
implements. It may have many objects. The soil
may be ploughed in order to turn under stubble, manure
and rubbish. It may be cultivated deeply and thrown
into ridges tor the purpose of drainage. It may be
stirred shallow in order to dry out the soil and to create
amulch. One cardinal object of tillage is to stir the soil
and expose it to air and light for their sanitary effect.

Lumpy soils need to be pulverized, sandy soils to be
packed. Sometimes, in planting small seeds, soil is
compacted in order to increase its capillary capacity and
to draw moisture to the surface from the subsoil as an
aid to germination. Whatever the ultimate result of
the tillage operation, all operations affect the soil in one
of two ways: either they loosen the soil and render it
more open and friable, or they pulverize and compact
it and make the structure denser. Choice of the proper

19

too] must be guided by the purpose for which it is to be
used. Jf the soil is to be turned over and the rubbish
covered, a mouldboard plough should be chosen. If the
operation is to reach deep into the soil a larger tool will
be required. In order to stir the subsoil a subsoil plough
may benecessary. In order to create a mulch on a sandy
loam soil we may select the weeder—a light tool which
very thoroughly stirs the soil to the depth of an inch.
On lumpy or stony soil a spring-tooth harrow or a large-
toothed cultivator may be necessary. In order to com-
pact the soil some form of roller may be used. The
kind of change to be effected in the soil should first be
determined, then the tool may be chosen which will best
accomplish the purpose.

All soil-working implements may be divided into
tour groups: (1) ploughs that invert the soil in addition
to effecting pulverization; (2) cultivators that stir
the soil; (3) pulverizers designed to reduce lumps and
level the surface; (4) compactors that bring the soil
particles closer together and smooth the surface.

; The plough.

The plough is the most efficient implement used on the
soil in proportion to the power required. It. operates
as a double, twisted wedge, which lifts and inverts a
ribbon of soil. (Fig. 36.) By this operation the furrow
slice is sheared or split into many thin layers both verti-
cally and horizontally ; the result of this process, when
properly done, is a complete pulverization of the soil.
Of course, the soil must be in the right moisture con-
dition for the best results, as has already been noted
(page 15);

Types of mouldboard.—The efficiency of the plough
depends much on its type and on the manner in which

20

itis used. (Fig. 43.) As a wedge it may have different
slopes or curvatures. For sod land, a long, slo ping mould-
board with a good overhanging is desirable, so that the
furrow will be gradually lifted and turned to its new
position in one continuous thread. Breaks and ragged
edges of the furrow permit it to be torn up by subsequent

GEAM CLEwTF

Mosing Coser Hees

Fic. 43.—The Plough. (1) Modern walking plough, with
parts named. (2) Types of mouldboard for (a) fallow
ground, light soil ; (b) fallow ground, clay soil ; (c) sod
ground ; (d) general purpose, fairly well suited to a wide
range of soil conditions. (3) Deep-tilling disc plough.
(4) Subsoiler. (5) Plough attachments: (a) jovnter,
(6) knife or beam coulter, (c) fin coulter, (d) rolling coulter.

21

preparation. On the other hand, for fallow land (bare
soil) a mouldboard with much greater curvature is used.
This accomplishes more thorough pulverization than
would the sod plough. Its draught is correspondingly
greater. Special types of plough are designed for work
on particular kinds of soil. On both sod and fallow iand.
a mouldboaid of intermediate curvature is employed.
The hillside plough has a peculiar shape of mouldboard,
hinged so that 1t can be turned to permit continuous
ploughing oa one side of the land, thus avoiding so much
uphill pulling by working across the slope. There is also
a considerable variety in the construction of these
implements, and different materials are used in the soil-
friction parts. For example, on gumbo clay a mouldboard
of special composition is required. Various modes of
construction are designed for supposed mechanical
superiority and convenience.

Right position of furrow.—In order to accomplish ee
ploughing, the furrow should be turned to the proper
angle, and should be reasonably straight. This requires
a particular proportion or relation between the depth and
the width of the furrow. (Fig. 44.) The best angle with
the surface of the subsoil at which to lay the furrow is
thirty to forty-five degrees. In order to obtain this
angle it is necessary that the depth of ploughing be about
one-half the width of the furrow. When the ploughing
is too shallow (one-third or less of the width) the furrow
slice is inverted. Stubble and -subbish are thereby
thrown in the bottom of the turrow, where they tend to
break contact with the subsoil and are poorly mixed
with the soil. On the other hand, when the furrow slice
is set well on edge there is fair chaace for capillary rise of
water, rainfall readily sinks into the soil along the face
of the furrow, and sod and rubbish are more thoroughly

22

distributed from the top to the bottom of the cultivated
soil. There is also better ventilation where decay should
be most active. At the same time the upper angle of
the inverted furrow slice may be easily pulverized and
worked into a good seed bed. When the soil bears a
heavy sod so that the furrow slice holds its form, heavy
rolling and packing are desirable so as to bring it in
closer contact with the subsoil and to avoid intersoil
spaces that are too large.

Depth of ploughing.—Most farmers in New York State
should consider deeper ploughing. Probably the average
depth is not over five inches. Much ploughing is even
more shallow than this. Particularly is deep ploughing
better on heavy soils and on those inclined to have a
compact subsoil. It crumbles their structure, mixes
organic matter more deeply, and as a result of both
processes moie water is retained and more plant-food
is available to crops. Deep ploughing is an efficient
means of increasing the general depth of root penetra-
tion; the deeper the roots are distributed, the more
uniform is the supply of moisture at their command and
the larger the food supply with which they are in touch.
On light sandy soil, deep ploughing must be accompanied
by the generous use of organic manures.

In the humid section of the country, where rainfall is
over twenty inches, the undisturbed subsoil, especially
on heavy or poorly drained soils, is likely to be infertile
for a time after being brought to the surface, owing to its
poor sanitary condition. In that section it is therefore
unwise to turn too much fresh soil directly on top in
any one season. Usually it is advisable to increase the
depth ot ploughing gradually at the rate of one-half to
one inch per year. This is best done in the fall.

The deeper the soil is ploughed, the more thoroughly

23

it is pulverized. Other things being equal, better results
are obtained from the same draught in deep than in
shallow ploughing. ; a

£=-90"°
yy, >
Uy

CPO

Fic. 44.—Diagrams illustrating the effect of depth of plough-
ing relative to width of furrow on the final position of the
furrow slice. The second and third are the most satisfac-
tory. When set in this position the upper edge of the
furrow slices may be readily worked down to a seed bed
without the interference of sod which may have been
turned under. Manure and turf are well distributed,
without breaking connection with the subsoil. Subsequent
packing and preparation should break down the lower edge
of the furrow slice and bring the topsoil in close contact
with the subsoil.

24

Draught of plough.—Tests by Professor C. A. O’Cock,
of the University of Wisconsin, warrant the following
conclusions concerning the operation of the ordinary
mouldboard plough :—

First, the draught perinch cross section of furrow cut
increases with the increased width.

Second, the draught per inch cross section of furrow cut
decreases as the depth is increased.

Third, the sharper the curve of the mouldboard, the
greater is the draught of the plough... Thus, a fallow-ground
mouldboard pulls harder than the sod type of the same
size.

Fic. 45.—An example of good ploughing. The soil is a
sandy loam. As good ploughing may be accomplished by
the use of a team and a walking plough as with this
tractor-drawn gang.

Fourth, when the soil is either too wet or too dry
the draft is increased over that for the soil in good
ploughing condition.

25

The draft of the plough will ordinarily be five to nine
pounds per square inch of cross section for the stubble
type, and four to eight. pounds for the sod type. Foca
six-by-fourteen-inch furrow the total draughtwould there-
fore be four to five hundred pounds in a soil in good
condition. Attachments, dull edges and stones in the
soil increase the draught.

Plough attachments.—Several attachments are used on
the plough for special conditions of the soil. (Fig. 43.)
On sod land the jointer much improves the result. This
is a miniature plough which cuts the surface roots and

es a5 5
= ws ea

>

Fic. 46.—A heavy chain attached to the whiffle-tree and the
beam of the plough, as shown 7m the illustration, is very
useful for turning under a heavy growth of vegetation on
the soil—as, for example, a green manure crop.

turns under the edge of the furrow, giving a smoother
appearance. It tends also to prevent grass from growing
along the soil line of each furrow.

Several types of coulter are used on sod or rooty ground
for cutting the furrow from the landside. All these
should be placed a little back of the plough point and
slightly outside the line of the landside, so as to cut a
clear course at the moment when the roots are drawn
taut over the point. The rolling and blade coulters are
attached to thebeam. Therolling coulter adds less to the

26

a ae

draught, andis more satisfactory than the blade coulter
where there is much surface rubbish. Occasionally, a
small fin coulter is attached to the share. When the
shin of the plough is sharp, especially on fallow ground
in good condition, coulters are of little service, and the
jointer in particular is objectionable owing to the
increase in draught.

Mouldboard versus disc ploughs.—There are two types
of turning plough, the mouldboard and the dise. The
former is in most general use and is adapted to the
widest range of soil cenditions. The dise plough is
especially suited to hard, dry soil, and does particularly
well where there is much rubbish or vegetation to be
turned under. It is not adapted to sod land or to soil
that is very stony. On stony land the cut-out disc is
preferred to the solid dise. On hard soil the dise plough
is more efficient than the mouldboard plough for the

_ draught consumed.

Subsoiling.—Subsoiling is the operation of breaking
up the subsoil without turning it to the surface. A
special plough is used in the bottom of the furrow behind
the turning plough. (Fig. 43.) Subsoiling is practised
most safely in the fall. Unsatisfactory results are likely
to follow subsoiling in the spring.

Deep-tilling implements.—An intermediate implement
between the turning plough and the subsoil plough
is the Spalding Deep-Tilling machine. (Fig. 43.) This
is of the solid disc type. There are two discs, one
behind and below the other. They are carried on a
sulky frame, and by proper adjustment the soil can
be worked twelve to sixteen inches deep. Its use
appears to be relatively more safe than would be plough-
ing with the mouldboard plough to the same depth, for,
although the subsoil is stirred, it is only partly thrown

27

to the surface and mixed with the topsoil. In order
to accomplish the mixing of the right proportions of
subsoil with the soil, special attention must be given
to the relative amount of cutting done by the two discs.

Double sulky plough.—The use of the double sulky
plough is increasing rapidly. This implement carries
two ploughs, one a right-hand and the other a left-
hand pattern, so that all the cutting is done from one
side. Dead furrows and back furrows, both of which
render the crop uneven, are thus eliminated. Sulky
ploughs, owing to their weight, are not suited to uneven
land where it is necessary to pull up the slope.

Cultivation

After ploughing, the soil should usually be worked down
and pulverized at once. At that time the lumps are
most easily pulverized, and by levelling and fining the
surface moisture is saved. In the case of fall ploughing
this practice is not recommended, as the rough surface
holds the snow during the winter and is less subject
to puddling during the spring thaws. Cultivators stir
the soil. For rapid work some type of harrow is gener-
ally used.

Harrow.—The harrow is a broad, many-toothed
implement, generally without wheels or guiding handles.
There are three main types of harrows: the spike-
tooth, the spring-tooth, and the disc. (Fig. 47.) The
spike-tooth harrow is light, and is therefore suited to
rather clean soil in fairly good condition. The spring-
tooth harrow draws to the ground better than does
the spike-tooth harrow. It works to greater depth and
tends to bring lumps and stones to the surface and to
collect roots and vines. Usually the slant of the teeth
of spike and spring-tooth implements can be readily

28

adjusted, and this determines the extent to which they
stir the soil. The weeder is a light type of the spring
tooth harrow, suited only to light, loose soils, where
shallow tillage is desired. The dise harrow, like the
dise plough,is more effective for its draught than are other
types of harrow. Especially is this true of the cut-out
and spading dises, which take hold of hard and stony
soil better than do the solid discs. The angle of opera-
tion of the disc can be adjusted, and this determines
the extent to which it draws to the soil and the extent
of pulverizing and turning. Its action resembles that
of the plough in that it tends to invert the soil.

The Acme harrow may be regarded as a fourth type.

Fic. 47.—T ypes of harrows. (1) Spike-tooth ; (2) spring-
tooth ; (3) weeder (spring-tooth constructor) ; (4) double
disc (note that the forward discs are solid while the rear
discs are of the cut-out type) ; (5) spading dise ; (6) Acme.
All these belong to the cultivator group of implements.

29

It consists of long, twisted blades. ‘It is a very useful.
tool onsoil free from stone, but its draught is relatively
large.

Cultivators, proper—The farmer usually makes a
distinction between harrows and cultivators. The
former are used in order to prepare the seed bed, the

=
a ——

Fic. 48.—Types of cultivators. (1) Wheel hoe, or hand
garden cultivator, with attachments ; (2) adjustable small-
tooth, one-horse cultivator, with duckfoot shovel behind ;
(3) two-horse spring-toothed cultivator; (4) two-horse
sweep or knife cultivator ; (5) two-horse disc cultivator.

30

Mires, 23

a ie ig a

‘

latter in order to cultivate or intertill the crop and to
kill weeds. The two types are, of course, interchangeable
according to crop and convenience. Cultivators that
have handles or other guiding arrangement are more
easily controlled by the operator. (Fig. 48.) There are
many patterns of these on the market, and in their
fundamental construction and operation they are much
like harrows. They may carry small spike teeth,
shovels of different size and shape, spring teeth, or
dises ; they may be swung on wheels with riding attach-
ment, and in the larger two-wheeled cultivators two or
more gangs are carried and guided by the feet of the
operator so that one or more rows are worked on both
sides at the same time.

The general practice now is to use cultivators carrying
many small shovels, so that the soil is kept level and
thoroughly stirred to a shallow depth. This type is
more effective in killing small weeds, in creating a mulch,
and in saving water than is the large-toothed type of
implement, such as the old fashioned single or double
shovel plough.

A type of shovel cultivator especially suited to cutting
off weeds and leaving an efficient thin surface mulchis the
duckfoot, wing, or sweep shovel. On stony or hard
soil this shovel cannot be recommended.

Pulverizers

Something more vigorous than a harrow is sometimes
required on lumpy soil ; grinding and crushing action is
most effective. For pulverizing and levelling the surface
the plank drag is effective. Clod crushers are a type
of corrugated roller, the weight of which may be con-
centrated on any resistant lump.

31

Packers

The most common tool used to pack the soil is the
roller, of which the log roller is the pioneer type. The
value of the roller depends largely on its weight and
diameter. For the same weight the smaller diameter
is more efficient than the larger diameter. The roller
is often used immediately after ploughing to press down
the furrow slices so that they will not be torn up by the
harrow and so that a more level surface is provided for
the team. In countries where the winters are severe
and the roots of plants are torn loose from the ground
by frost, the roller is used in order to press roots into the
soil and to firm the soil around the roots so that they
may renew their growth. Rollers usually are made in
two or more sections for convenience in turning, and
have a basket or some other arrangement for loading
in order to increase the weight. As a pulverizer the
solid roller is inefficient. (Fig. 49.) Its weight is
distributed over too much surface and it is likely to press
the clods into the soft soil rather than to crush them.

Another type of roller is the subsurface packer, which
comes near to being an ordinary clod-crusher. Its
surface is broken so that it cuts into the soil and exerts
pressure to a considerable depth. It is especially useful
in the spring of the year and in arid regions, in pressing
the furrow slice into close contact with the subsoil
and at the same time leaving a loose layer of soil on the
surface as a mulch to save water.

Special soil-working tools

There are a number of instruments designed for use
in special crops or under special conditioas. Among
these may be mentioned: (a) the lister, which ploughs

32

Tec CeiCecccceciey

f

Fic. 49.—Types of packers and pul-

verizers.

(1) Solid or barrel roller ;

(2) corrugated roller ; (3) crusher

and subsurface packer ;

roller.

(4) bar
33

and plants at the
same time, used
mostly under semi-
arid and _ pioneer
conditions ; (b) the
grape and berry hoe
for working close to
small fruits ; (c) the
adjustable dise for
reaching under trees
with low-hanging
limbs. It should be
said also that many
seeding implements
cultivate and _ pul-
verize the soil in the
process of planting
the seed. The giain
drill, in particular, is
of this sort.

Special’ soil
conditions

There may be
many special condi-
tions of soil or
subsoil, of season or
crop or equipment,
which require
peculiar treatment,
so that always the
purpose to be accom-
plished should deter-
mine the use of an
implement. If the

soil were a little too wet it might be thrown up
in high ridges with a large shovel plough in order
to hasten the evaporation of water. In an old orchard
long in sod, ploughing should be shallow in order
to avoid injury to the roots of trees. In the late
fall a soil may sometimes be safely ploughed while

Fie. 50.—The planker. A home-made implement that is
very efficient in pulverizing the soil and smoothing the
surface. Its pulverizing action in connection with a
toothed harrow is often more efficient than the roller.

in a very wet condition, when winter freezing is

depended on to counteract any possible puddling.
In windy regions sandy soil should not be fall-ploughed,

since itis likely to be blown away. In parts of the South-

34

west, ploughing in large ridges is found to be more
successful in saving moisture than the formation of
a level surface, because such ploughing prevents the
wind from carrying away so much soil and thus conserves
moisture.

Circumstances will always alter cases. It is impossible
to lay down fixed rules in the handling of the soil, even
tor a particular farm, because of the many conditions
involved. There is required on the part of the farmer

- an understanding of the principles involved, keen observa-

tion, and good judgment, in order to know what combina-
tion of treatments will give the best results at the least

cost.
An important object of tillage is to kill weeds, because

weeds rob the regular crop of moisture, food, sunlight,

and air. Weeds are most easily overcome when small,
and sometimes rough tearing up of the soil and waste

_ of moisture through exposure is justified in order to
cover and to kill the weeds. This is a common means

of overcoming small weeds in the row.

Tillage by dynamite
A type of tillage that is now much advertised for
soils inclining to a hardpan structure is the use of
dynamite. The explosion of small charges of dynamite
at frequent intervals (ten to twenty feet) in the subsoil,
at a depth of two or three feet, is said to loosen the soil
much as though asubsoil plough had beenused. (Fig. 51.)

‘Whether to use dynamite or a plough is a question of

cost and efficiency where such a condition of soil exists.
In either case the soil should be relatively dry. Dyna-
mite has the advantage on stony soil and may be more
efficient for deep work, but the cost per acre is high as
compared with tillage operations and the question

35

arises whether there are many areas of soil in New York
State where the treatment is justified. Unless it breaks
through the hardpan soil to some porous layer below,
dynamite is likely to make drainage conditions worse
rather than better, and on the great majority of New
York lands its use fer this purpose has no place.

ee : an SOY ; : 4 vie oj
: KY oS > =a ST a: at ‘4 :
HARDPAN S72 x
oe SS

<< LBS

Fic. 51.—Section of soil illustrating the proper position of
a charge of dynamite with reference to a hardpan layer,
and its supposed action in breaking up a compact condi-
tion. For efficient results the subsoil should be dry.
(Sketch by Du Pont Powder Company.)

Thorough drainage, which costs little more, will in time
have much the same effect on the subsoil, and it produces
more generally desirable and permanent results. The
best results on very hard soil are likely to follow the
combined use of dynamite and drainage. Dynamite
should be used first. ,

In conclusion, it should be remembered that cultivation
and all the operations that aid in maintaining good tilth

36

contribute to the ventilation of the soil and are especially
beneficial in their sanitary influence. Stirring and
turning and thorough preparation before seeding,
together with as much tillage as possible during the grow-
ing season, are essential in order to keep every active soil
in a healthy, fresh condition. If little cultivation is
possible, it is more important before planting. The
intelligent tarmer knows that the prize crop usually
follows the most thorough preparation of the soil. He
works the soil cover and over even after it seems to be in
good tilth. Jethro Tull, the shrewd English farmer of two
centuries ago, was wise beyond his day when he said,
“Tillage is manure.’”’ It is manure and it is health
to the soil. Centuries before the time of Tull, Virgil
had written the same experience into his verses descriptive
of Roman husbandry :

“Much more advantage to the swain it yields
~ To use the rake, than harrow sterile fields :
Nor golden Ceres, from the lofty skies
Shall view his labour with regardless eyes.
And who, athwart the furrows, ploughs the plain,
Then breaks the clods obliquely o’er again,
Turning his team, and by a frequent toil,
To obedience brings a disobedient soil.”

Sometimes better results have followed hand work
with fork and hoe than the use of larger implements.
This may be attributed to the deeper and more thorough
preparation of the soil in hand.work, and emphasizes
the well-observed fact that thorough tillage is a prime
requisite for good crops.

37

ADVANCED READING

The Correspondence-Course lessons are designed merely
to introduce the subject; they are elementary and
brief, and are intended to arouse a desire for fuller
knowledge along particular lines. The study of
Correspondence-Course lessons should be introductory
to the study of standard agricultural books and of the
bulletins of the Dominion Department of Agriculture
and the State experiment stations. The Supervisor of
the Correspondence-Course wil] suggest, as far as possible,
agricultural literature to meet the needs of any reader.
Particular books or bulletins are recommended because
they are thought to be of special interest to the reader
in his individual study and not because they are
considered superior to others on the same subject.

Principles of soil management. T. L. Lyon and

E. O. Fippin. Pages 68-119, 465-497. The

Macmillan Company, New York City’ .. .. $1.75
Fertilizers and crops. L. L. Van Slyke. Pages

89-104. Orange Judd ei bes New York

City > itis Lee 2.50
Farm machinery sama: bese iS. J. B. David-
- sonand L. W. Chase. Pages 51-101. Orange

Judd Company, New York City .. 2.00
Physics of agriculture. F.H. King. Dice 108-

128, 223-254. Published by the author, Madi-

son, Wisconsin .. . os (aa 1.75
Bulletins, United States Bee of Soils :

No. 50. Moisture content and the physical condition
of soils.

No. 82. The effect of soluble salts on the physical
properties of soils. (Distributed by Superintendent
of Documents, Washington, D. C., at a nominal
price.)

38

Farmer’s Bulletins :
No. 421. Control of blowing soils. (Free on applica-
tion to Senators or Representatives in Congress, or
to the Secretary of Agriculture, Washington, D.C.)
_ Bulletins, Kansas Agricultural Experiment Station
(Manhattan, Kansas): No. 127. The roots of plants.

mmetts AND TILLAGE OF THE SOIL

DISCUSSION PAPER

The Discussion Paper is planned to help the student
by drawing his attention to the important points of
the subject he is studying. It is intended to develop
thought and self-expression of his own ideas. Each
Discussion Paper, when answered and returned, is
carefully read by the staff of the Department of Agri-
culture and a personal statement is given in connection
with any question that the reader thinks the student
has not fully understood. The student is invited to
ask any questions that will help to give him a more
complete understanding of the Course.

GENERAL INSTRUCTIONS

Always express your ideas in your own words.

Finish one paper at a time.

3. See that the subject is placed at the top of the first
page of each paper answered.

4. Do not torget to write your NAME, NUMBER, and
COMPLETE ADDRESS, on each set of answers.

5. Number each question, and also each sheet, and pin
them together in their right order.

6. Send in each paper as soon as completed.

par

39

10.

QUESTIONS

Should land be worked as soon as it is fit in the
spring. Why ?

What happens to a heavy loam soil that is worked
when it is too wet? Mention what you would
do with land that had been worked when too damp.

Describe how you would determine when to start
work on the land in the spring.

Explain the advantages of securing a granulated
structure in a clay soil. Mention some of the
methods of obtaining this structure.

Discuss the advantages of drainage and state how
you would decide that a piece of land needed
draining.

Will land in need of drainage retain as much avail-
able soil moisture during a continued dry spell
as will drained land? Why ?

Describe soil conditions that require shallow
ploughing and others that require deep ploughing.

Describe soil conditions that would be helped
by the use of a subsoil plough. What time of
the year would you do the work ?

Describe the use of the different types of harrows
and cultivators you are tamiliar with, stating
soil conditions in which they can be used to best
advantage.

Name, and describe the locality you propose
to farm in, and state how you would prepare
your land for wheat. What implements would
you use, and in what order? Under what
conditions would a roller or a packer be used,
and at what season.

40